Interpretive Summary: Long-term storage of perishable commodities is a means to assure out-of-season market availability to consumers. Extending the storage life of pear fruit requires technology that preserves edible quality while preventing development of disorders that cause fruit to be unsalable. Research was conducted to examine if storage conditions exist to allow pears to be stored for 8 months without development of disorders. A set of conditions whereby pears were held in cold storage with very low oxygen concentration allowed fruit to be held for 8 months without development of a common peel disorder was identified. However, this storage protocol did not allow all fruit to soften normally, and some fruit developed a unique peel disorder not often occurring in typical commercial practice. Further research is required to determine if a low oxygen protocol exists that allows normal ripening in the absence of disorder development after long-term storage of pears.

Technical Abstract:
‘d’Anjou’ pears, a superficial scald-susceptible cultivar, were stored in air or controlled atmospheres containing 1.5 kPa O2 or a minimal partial pressure determined using real-time monitoring of fruit chlorophyll fluorescence. In two experiments, the low O2 setpoints were 0.4 and 0.5 kPa. During experiment 1, pears stored continuously at the low O2 setpoint did not develop superficial scald (scald) while scald developed on fruit stored in air, 1.5 kPa O2 , or 0.5 kPa O2 for 6 months then 2 months at 1.5 kPa O2. Fruit from 2 of 3 lots stored in 0.5 kPa O2 during year one of the two year study developed peel black speck, a disorder previously reported on d’Anjou fruit stored in O2 concentrations of 1 kPa or below. All CA environments slowed peel color change with the low O2 concentrations having a larger effect on color after longer storage durations. Fruit softening was also reduced by the low O2 concentrations compared to fruit stored in air or 1.5 kPa O2. Fruit stored in 0.4 kPa O2 with 0.1 kPa CO2 in experiment 2 did not soften to a commercially acceptable value during the shelf life period after removal from storage. The results indicate low O2 partial pressure established using fruit chlorophyll fluorescence can prevent ‘d’Anjou’ scald but may result in black speck development as well as insufficient softening during a typical shelf-life period.